To assess the impact of NMDs, including secondary mitochondrial dysfunction, on the specificity of the two biomarkers, this study examined the GDF15 and FGF21 concentrations in patients with non-mitochondrial neuromuscular disorders, including viral encephalitis, myasthenia gravis, DMD, and epilepsy, with the latter two being frequently associated with secondary mitochondrial dysfunction. This evidence concerns the gene GDF15 and myasthenia gravis.